Apparatus for and method of loosening a threaded connection



Apnl 28', 15959 v J. "c. BENDER f 2,884,065

APPARATUS FOR AND METHOD OF LOOSENING A THREADED CONNECTION Filed Nov. 1s, 1955 2 sheets-sheet 1 da/7 C. BenQ/ef* NVENTOR.

April 28, 1959 .1. C. BENDER APPARATUS FOR AND METHOD 0F LoosENING A THREAD@ coNNEcToN Filed Nov. 18, 1955 2 Sheets-Sheet 2 .f @.R. a 4 M J .J 6V .Bm 1.1M 1 1 1 1 1 1 1 111 |1.\,1 l 1 I 1 l I |11 n A ,m 111/ ...B y 1 2. 411 y M, AWV y, 31; M A@ ,1 v Il; 1 1 M 31 y M Y, 2,884,06 Patented Apr. 28, 1959 APPARATUS FOR AND METHOD OF LOOSENING A THREADED CONNECTION John C. Bender, Houston, Tex., assignor-to Houston (lil Field Material Company, Inc., Houston, Tex., a corporation of Delaware Application November 18, 1955, Serial No. 547,772

11 Claims. (Cl. 166-36) The present invention relates to a method of and apparatus for loosening a threaded connection in a string of pipe and more particularly relates to a method of and apparatus for initiating the unthreading of a string of pipe at a threaded connection in a well bore by the use of directed explosive forces. y

In the drilling of oil, 'gas and sulfur wells and the like the operator is frequently confronted with the problem of having a string of pipe, such as drill pipe, become stuck in the Well bore. In such cases it is highly desirable to provide a method of and means for disconnecting one or more threaded connections above the stuck point so that the portion of the pipe that is not stuck' can' be removed from the Well bore and iishing or other operations performed to recover the stuck pipe, if possible.

To this end various methods and devices have been devised, such as the method described in U.S. Patent No. 2,305,261, issued December 15, 1942, to'Myron'M. Kinley for a method of removing pipe from wells in which an explosive charge is suspended in the pipe adjacent the connection desired to be Unthreaded and isy detonated While the pipe is torqued from the surface of the earth in `a direction tending to unthread the connection. lSuch a method and means is also disclosedfin my Patent No. 2,686,039, issued August 10, 1954, entitledMethod of and Apparatus for Determining Physical Properties of Materials. i

The methods and devices of the typ'e justdescribed, as well as others, depend upon the uncontrolled forcefof an explosive or an impacting force adjacent the threaded connection to cause jarring in the vicinity of theconnection which is combined with torque placed onthe pipe by mechanical means from thesurface of the earth in a direction tending to unthread the connection.

It is a general object of the present -inventionfto pro-- vide a method for and a means of directingthe 'force of an explosion within a string of pipe `so that these explosive forces themselves tend to loosenhand in som instances disconnect the threaded connection.

Another lobject of thefpresent'inventionv is the provision of a method of and means forloosening a threaded connection in a string of pipe byy providing means for and placing an explosive within'the string of pipe On one side of the connection and -another explosive within the pipe on the other side of the connection, the two -explol sives being secured against relative rotation, and upon detonation of the explosives jetting the force of each explosive against the internal wall of the stringofpipe in opposite directions tending to unthread the threaded connection. f

Still a further object of the present invention is to combine with the directedjet action of-the explosive forces an additional torque force tending to unthread the threaded connection. v 1

And yet a further object of the present invention is to .provide suchy ay methodl'and-,.apparatue'.inllwhichithe method is simple and efficient and the apparatus is rugged and economical to use, construct and maintain.

, Still further features, objects and advantages will be apparent from the following description of an embodiment of the invention.

rvThepresenty Vmethod and apparatus areparticularly, but noty necessarily, adapted for loosening threaded con# nections of'stuck pipe in a well bore |and the description of presently preferred embodiments are directed toward that 'use although other uses and adaptations of the invention will readily suggest themselves to those Askilled in the various arts. 4 'Accomplishrnent of the above and other objects will be apparent to those skilled in the art from the following description when taken in conjunction with the' accompanying drawings, wherein like reference characters refer'to like parts throughout where: f

Figure l is an elevational view illustrating an apparatus laccording to the present invention in y,place in a well the several views, and

fcasing,

' Figure 2A is an enlarged fragmentary elevational View, in section, of the upper part of a device of Figure 1,

Figure 2Bfis a 'continuation of Figure 2A and illustrates the lower portion of the device of Figure l,

Figure 3 is' a cross-sectional view taken along the line 3-3 of Figure 2A, and f Figure 4 is a cross-sectional view taken along. the line 4,44 of Figure 2B.

YReferring now to the drawings, and particularly"A to Figurell, the apparatus includes an elongate body 8 adapted to be inserted and moved in a string of pipe' in a well bore, a first or upper set of explosive guides such as jet 'ports 10 in the body 8, a rigidl mandrel 12as part of the body 8, and a second or lower set of explosive guides such-as jet ports 14 in the body 8, the jet ports being axially spaced and oppositely directed. This appa ratus may be designated as a torque gun and is hereafter referred to as such.` V i `In Vuse, the torque gun, as is shown in Figure 1, is placed in a string of pipe 16, such as `drill pipe used in an-oil well, with-the first set of explosive guides or jet ports 10 above a threaded connection 18 and with the seconds'et of explosive guides or` jet ports 1,4- below the threaded connection 18 at the place where it is desired to disconnect the pipe 16. Ordinarily, this will bethe first-free joint above a stuck portion of the pipe 16, which pointmay be located previously or concurrentlywith a suitable indicator. As mentioned previously, 'the ytrst set'of-jet ports 10 are directed oppostely to those of the vsecond set of jet ports 14Aand relative movement'between these two sets of jet ports is prohibitedy by the rigid mandrel 12 so that the full force of explosive jets erupting from the jet ports is directed against the wall of the pipe 16 and the jet forces are not dissipated by the reaction to such forces causing a yspinning action o f parts of the torque gun. The oppositely-directed jet ports are so directed that detonation of the torque gun applies jet forces to the pipe 16 in directions tending to unthread the pipe.v If desired, a torque may be applied to the I pipeat the surface tending to assist in initiating threading of the joint.

Referring now to Figures 2A and 2B a presentlypreferred'torque gun is illustrated in detail in which the iirs't yset of jet ports 10 are contained inthe body 8 kini a series of enlargements 20 which enlargements' 20` are like set of enlargements 22.

the drawings the explosive means is illustrated as any suitable flexible cord-type explosive 24 such as the Well In the particular Vform of 'the' invention*illustratedin known- Primacord, such as that manufactured byf'the Ensign-Bickford Company, Simsbury, Connecticut, which,

generally speaking, is composed of a hollow fabric' or plastic tube, the bore of lwhich is lled with one of the well known detonatable chemical explosives such as pentaerythritoltetranitrate, which may be red by applying a detonating shock at onefend, the detonating'wave traveling sufficiently rapidlythrough the length of the cord to produce substantially simultaneous detonation throughout the whole length ofthe explosivevcomprising the cord. To easily receive the cord-type explosive 24 the upper set of jet ports include the g-rooves or slots 26 which are directed in one direction, the lower set of jet ports 14 being likewise grooves or slots 28 directed in an opposite direction. The direction of these grooves or slots and the placement of the cord-type yexplosive therein can best be seen in the cross-sectional views of Figures 3 and 4. Turning again to Figures 2A and 2B, both sets of grooves 26 and 28 are perpendicular to the axis of the pipe 16 so that jet force coming out of the grooves 26 and 28 are directed against the inner-wall Lof taped 1to theside of themandrel`12 to hold -itiinpos'ition Asy thewell duid normally present in the well bore y may'A leak "through the opening 50 into the chamber 36 the. string of pipe 16 along a length 'of the pipe above and below the joint 18. Since both sets of'jet ports `10 and 14 are. stationary with respect to one another, the jetting force lfrom the grooves 26 and 28 is oppositelyy directed against the inner wall of the string of pipe 16 at points above and below the joint 18 in a direction tending to cause the joint 18 to become Unthreaded or to initiate unthreading thereof.

The enlargements 20 and 22 are advantageously provided to bring the mouths of the grooves 26 and 28 in close proximity to the inner wall of the string of pipe 16 to'make more effective use of the jetting force. The reduced diameter portion 30 of mandrel 12 is provided between both the first set of enlargements 20 and the second set ofenlargements 22 so that the cord-type explosive may be securely held within and against the basel of the slots 26 and 28 as this reduced diameter portionI 30 provides a convenient place for this purpose, such as by the'tape 32. If the enlargements 20 and 22 are unduly extended in length, there is some danger of the cord-type explosive 24 slipping away from the base of the grooves 26 and 28. Likewise, the tape 34 around the mandrel-12 is Iused to hold the cord-type explosive in-place along the mandrel between and beyond the upper or first set of enlargements 20 and the lower or second set 22. Of course other means for securing the cord-type explosive 24 in place could be used such as metal straps and the like.

Thedetonating means for the cord-type explosive 24 is best illustrated in Figure 2A. As shown there the upper end of mandrel 12 is hollow to form the chamber 36 with the upper portion of this chamber 36 receiving the lower end of a shooting head 38, which shooting head 38 is threadedly secured to the upper end of the mandrel 12l by the complementary threads 40. Passing longitudinally through the shooting head 38 is an electrical conductor42 which extends into the seal assembly, generally indicated by the reference number 44, which extends below the lower end of the shooting head 38. The electrical conductor 42 makes electrical contact with lead wire 46 through a contact 48 within the seal assembly 44. This lead wire 46 passes out of chamber 36 through an opening 50 in the wall of the mandrel- 12 to a conventional detonator 52. The electrical circuit to detonate the detonator 52 may be completed in any preferred manner, such as grounding the detonator 52 to the wall of the mandrel 12 and having another electrical conductor in electrical contact with the' shooting head 38. Any suitable source of electrical energy and switching arrangement well known tothe arty may be used for supplying electrical energy for detona-l tion. Asshown in Figure 2A, the detonator 52 is pref- 'i tained in tube 54 taped to the exterior of mandrel 12.`

in the upper part of mandrel 12, the portion of the lead wire 46 adjacent the seal assembly 44 and seal assembly 44 are taped as at S6 for insulation and to help hold the lead wire 46 in position against the electrical contact 48. Referring now to Figure l, the shooting head 38 is shown having a shoulder 58 to which a wire 60 or other type of line may lbe attached for lowering or raising the torque gun within the casing 16. Also, a conventional electrical connection is made with the detonator for detonating the same. Since any desired electrical connection can be made and there are numerous ones available, no detailed description thereof is deemed necessary. It is obvious that iffor some reason it should be desired to utilize a torque gun with a string of pipe, the upper end of the shooting head 38 could have threads adapted to be threaded into the string of pipe. In operation the cord-type explosive 24 is placed in the grooves 26 and 28 and held there by tape in the reduced diameter portions 30 and along the length of the mandrel 12.

ments 20 and placed in contact with detonator 52 con#v The lead wire is electrically connected to the electrical conductor 42 and the shooting head 38 secured to the upper end of mandrel 12. The torque gun isy then lowered into the casing 16 by the Wire line 60 until it erably placed in a tube 54 into which the upper end of v a length of cord-type explosive 24 is inserted to make contact with the detonator 52. This tube 54 is `then lwithy its lead wire 46 is installed.

reaches the position shown in Figure 1 at which time the cord-type explosive 24 isv detonated causing oppositely directed explosive jet forces to corne from the grooves 26 and 28 and -be directed in opposite directions againstv the inner wall of the casing 16 causing explosive torque to be applied to t-he casing 16 to at least initiate unthreadingV of the casing 16 from the coupling 18. If desired,

as previously mentioned, additional torque may be ap-I plied to the string of pipe when the explosive is detonated in a direction tending to unthread the connection 18 to aid in unthreading this connection 18. This additional torque may be applied in any way well known to the art such as by a rotary table, not shown, at the surface of the earth. `While not necessary, the explosion of the cordtype explosivel through the joint may assist in impacting or jarring the joint.

After the cord-type explosive 24 and the detonator 52 have been exploded and the torque gun removed from" the pipe` 16 the shooting head 38 is unthreaded from the upperend of the mandrel 12, and a new detonator-52 Additionally, new cord-type explosive is inserted in the tube 54 and placed in the grooves 26 and 28 and taped in position as has been previously described. The torque gun it then ready for use again.

It, seems obvious from the foregoing description of they invention that various types of detonating assemblies.

could :be used to detonate the cord-type explosive 24 from` that described in the preferred form of the invention lwithout departing from the spirit of the invention.

Further, the jet ports 10 and 14 may have other shapes than grooves and other types of explosives than cordtype explosive may 'be used. However, as cord-type exi plosive is easily available and as the grooves 26 and 28 are easily out an inexpensive and reliably efficient torque gun is provided by the presently-preferred torque gun illustrated.

jIt seems obvious that while a preferred form of the apparatus is given other apparatus could be used in the vmethod, of the present invention of which the basic concept is the application of oppositely-drected explosive jet forcesfto, thev interiorfwall. of a string of pipe oneach side of a threaded connection tending to unthread the 'threaded-connection.'

The various lengths of cord-type explosive arel joined near the upper end of the uppermost enlarge-l In someinstancesit may only be necessary to apply the jet force in one direction above or adjacent the threaded connection desired to be Unthreaded as the stuck portion of the pipe on the other side of the connection serves as a back up for the directionally-applied unthreading force. Thus, the method and apparatus of the invention encompasses this aspect thereof.

It is therefore apparent that the present invention is well adapted to carry out the objects and attain the ends and advantages set forth as well as others inherent therein. Also, numerous changes in details of construction, arrangement of parts and steps of the process may be made which will readily suggest themselves to those skilled in the art and which are encompassed within the spirit of the invention and the scope of the appended claims.

What is claimed is:

1. An apparatus for loosening or disconnecting a threaded connection in a string of pipe comprising an elongate body adapted to be moved in a string of pipe, first and second guides for directing explosive jet forces from the body carried by the body in longitudinally spaced relationship with respect to one another so that when the elongate body is placed in the string of pipe adjacent a threaded connection the first said guide is disposed on one side of the threaded connection and the second said guide is disposed on the other side thereof, each said guide arranged in a plane generally perpendicular to and radially spaced from the axis of the body and intersecting the outer surface of the body at an acute angle thereto, said first guide being directed in an opposite direction to the second guide, explosive means in the guides, and means to detonate the explosive means.

2. Apparatus for loosening or disconnecting a threaded connection in a string of pipe comprising, a first explosive force-applying assembly including a first guide for directing explosive jet forces from the rst assembly, said first guide arranged in a plane generally perpendicular to and radially spaced from the axis of the string of pipe when disposed in the pipe; a second explosive forceapplying assembly including a guide for directing explosive jet forces from said second force-applying assembly, said second guide arranged in a plane generally perpendicular to and spaced from the axis of the string of pipe when disposed in the pipe and in an opposite direction from the first guide; said guides intersecting the outer surface of said assemblies at acute angles thereto; and a rigid member connecting said explosive force-applying assemblies in spaced relationship.

3. In an apparatus for loosening or disconnecting a threaded connection in a string of pipe, the improvement comprising a support for lowering and moving the apparatus in the pipe, an explosive jet assembly carried by the support, said explosive jet assembly including a guide for directing an explosive jet force from the explosive jet assembly, said guide arranged in a plane generally perpendicular to and radially spaced from the axis of the string of pipe when disposed in the pipe, said guide intersecting the outer surface of the support at an acute angle thereto.

4. Apparatus for loosening or disconnecting a threaded connection in a string of pipe comprising, an elongate body adapted to be moved in the string of pipe, first and second sets of jet ports disposed in longitudinally spaced relationship with respect to one another on said elongate body so that when the elongate body is placed in the string of pipe adjacent a threaded connection the first set of jet ports is disposed on one side of the threaded connection and the second set of jet ports is disposed on the other side thereof, the jet ports in each set being directed in one general direction in a plane generally perpendicular to and radially spaced from the axis of the body, each said set of jet ports being arranged to direct its jet forces in an opposite direction to the other set of jet ports thereby loosening the threaded connection, explosive means in the jet ports, and means to detonate the explosive means.

5. An apparatus for loosening or disconnecting a threaded connection in a string of pipe comprising, a mandrel adapted to be moved in the string of pipe, first and second sets of longitudinal slots in axially spaced relationship with respect to one another in the exterior of said mandrel so that when the mandrel is placed in the string of pipe adjacent a threaded connection the first set of slots is disposed on one side of the threaded connection and the second set of slots is on the other side thereof, the slots in each set being directed in one general direction in a plane generally perpendicular to and radially spaced from the axis of the mandrel, each such set of slots being directed in an opposite direction to the other set of slots, explosive means in the slots, and means to detonate the explosive means thereby directing jet force against the interior wall of the string of pipe in opposite directions on each side of the threaded connection thereby initiating unthreading of the connection.

6. A method for loosening or disconnecting a threaded connection in a string of pipe comprising the step of applying jet forces to the interior wall of said string of pipe on each side of the threaded connection and in the direction and at an angle to the interior wall of the pipe to unthread the threaded connection thereby initiating unthreading thereof.

7. A method of loosening or disconnecting a threaded connection in a string of pipe comprising placing a first explosive means directed approximately perpendicular to the axis of the string of pipe at an angle to the interior wall thereof and in the direction to unthread the threaded connection within the string of pipe on one side of the threaded connection, placing a second explosive means directed approximately perpendicular to the axis of the string of pipe and in an opposite direction to the first explosive means within the string of pipe on the other side of the threaded connection, and detonating the explosive means thereby directing explosive jet forces against the string of pipe in opposite directions on each side of the threaded connection thereby initiating unthreading of the connection.

8. The method of claim 7 wherein the explosive means is cord-type explosive.

9. The method of claim 7 including applying additional torque force to the string of pipe when the explosive jet forces are applied.

10. In a method of loosening or disconnecting a threaded connection in a string of pipe by applying an explosive force against the threaded connection, the improvement comprising directing the explosive force generally tangential to the pipe adjacent the threaded connection and in the direction to unthread the threaded connection.

11. In an apparatus for loosening or disconnecting a threaded connection in a string ofy pipe, the improvement comprising an elongate body adapted to be moved in a string of pipe, rst and second guides for directing explosive jet forces from the body carried by the body in longitudinally spaced relationship with respect to one another so that when the elongate body is placed in the string of pipe adjacent a threaded connection the first said guide is disposed on one side of the threaded connection and the second said guide is disposed on the other side thereof, each said guide arranged in a plane generally perpendicular to and radially spaced from the axis of the body, said first guide being directed in an opposite direction to the second guide, said guides intersecting the outer surface of the body at acute angles thereto.

References Cited in the le of this patent UNITED STATES PATENTS 2,305,261 Kinley Dec. 15, 1942 2,326,114 Zschokke Aug. 10, 1943 2,725,820 McCullough Dec. 6, 1955 2,745,345 Sweetman May 15, 1956 

